Parallel Capacitor Breakdown Detection Using Temperature-Tracked Capacitance
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Solution Overview
Problem
Existing methods fail to reliably recognize the breakdown of one energy reserve device in systems with two or more electrolytic capacitors connected in parallel, due to differing nominal capacitances and production-related capacitance tolerances.
Innovation Solution
A method that charges the energy reserve devices to a test voltage, acquires the ambient temperature, and recognizes breakdowns by comparing the overall capacitance with a temperature-dependent mean value, using a floating mean value that is updated based on the acquired capacitance and ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional breakdown recognition methods are used in systems with two or more electrolytic capacitors connected in parallel, then the system can operate with multiple capacitors providing energy reserve, but the breakdown of an individual capacitor cannot be reliably detected due to capacitance tolerances and nominal capacitance differences
Solution Approach 1:
The patent segments the capacitance measurement problem by measuring each capacitor's capacitance individually rather than measuring the total capacitance of the parallel combination. This allows identification of individual capacitor breakdown while maintaining the parallel configuration for energy reserve operation.
Solution Approach 2:
The patent changes the measurement parameter from total capacitance to individual capacitance values, and introduces temperature as a compensating parameter. By measuring and compensating for temperature effects on capacitance, the system can reliably detect actual breakdown conditions despite temperature variations affecting all capacitors.
2Measurement precision
If the capacitance of energy reserve devices is measured to detect breakdown, then breakdown can be detected, but temperature variations cause capacitance changes that lead to false detection due to the 15% temperature dependence from -40°C to +105°C
Solution Approach 1:
The patent implements feedback by continuously monitoring the temperature of the energy reserve devices and using this temperature information to compensate for its effect on capacitance measurements. The system adjusts the evaluation criteria based on the measured temperature, preventing false breakdown detection caused by thermal capacitance variations.
Solution Approach 2:
The patent changes the measurement approach by introducing temperature as a controlling parameter. Instead of using fixed capacitance thresholds, the system dynamically adjusts capacitance evaluation based on the measured temperature, accounting for the 15% capacitance variation across the -40°C to +105°C range.
3Use of energy by moving object
If electrolytic capacitors are used for energy reserve due to their large capacitance, then sufficient energy reserve is provided, but production conditions cause capacitance tolerances between 0% and 30% nominal tolerance that prevent reliable breakdown recognition
Solution Approach 1:
The patent segments the capacitance evaluation into individual capacitor measurements rather than relying on total capacitance. By measuring each capacitor's capacitance separately and comparing it to its specific nominal value and temperature-compensated reference, the system can identify breakdown in individual capacitors despite the 0-30% manufacturing tolerances.
Solution Approach 2:
The patent changes the evaluation parameter from absolute capacitance values to relative capacitance changes. By monitoring deviations from temperature-compensated reference values and using floating mean values, the system can detect actual breakdown conditions despite the wide manufacturing tolerance range of the electrolytic capacitors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method securely and reliably identifies the breakdown of at least one electrolytic capacitor in parallel systems, preventing disturbances in the occupant protection system and ensuring timely correction before energy reserve levels fall below minimum requirements.
Implementation Method 1
the capacitances of the energy reserve devices are a function of temperature
Implementation Method 2
A temperature dependence of approximately 15% in the temperature range from −40° C. to +105° C.
Data Source
AI summary
A method for recognizing the breakdown of an energy reserve device of at least two energy reserve devices of a device for protecting the occupants of a vehicle. The method includes: charging the at least two energy reserve devices to a test voltage level; ascertaining an ambient temperature of the at least two energy reserve devices; acquiring the (overall) capacitance of the at least two energy reserve devices; recognizing the breakdown of an energy reserve device as a function of a floating mean value, which is a function of the ascertained ambient temperature, for the (overall) capacitance and of the acquired (overall) capacitance; updating a floating mean value as a function of the ascertained ambient temperature and the acquired overall capacitance.